The invention relates to a motor vehicle for industrial and/or agricultural applications, in particular for an agricultural tractor, with an attachment interface containing a three-point implement hitch at either the rear end or front end of the vehicle.
Agricultural tractors in particular, but also other utility vehicles employed in agricultural or industrial application, are used primarily as working machines for performing operations in the field. For this purpose an appropriate implement can be attached to the vehicle. In contrast to single-purpose machines, the tractor is therefore an open system that can become a machine capable of useful operations by being coupled to an implement.
Since a work vehicle should be capable of being coupled to various implements for the performance of various operations, the attachment interface between the motor vehicle and the implement takes on a particular significance. The term attachment interface is understood to include all devices that are required in order to couple implements to the motor vehicle and, if necessary, to supply them with propulsion power.
A usual attachment interface, with which most agricultural tractors and similar agricultural motor vehicles are equipped today, contains a so-called three-point implement hitch as it is defined, for example, by standards ISO 730 or DIN 9674. Such a hitch includes two lift arms, connected to each other by a lift shaft, each of which engages an associated hydraulic power lift cylinder. Each lift arm is connected through a lift rod or a lift spindle with an associated lower steering arm, which carries a lower coupling point. Furthermore, the three-point implement hitch contains an upper steering arm connected in a joint with the tractor body with a third, central, upper coupling point.
The three-point implement hitch makes it possible to mount implements by simple means to the agricultural tractor. For this purpose the tractor is driven up to the implement previously deposited on the ground. The coupling points are coupled to corresponding recesses of the implement, so that the utility vehicle and the implement form a fully-functional processing unit. If necessary, a power take-off shaft of the utility vehicle is connected with the input shaft of the implement. Electrical and hydraulic connections for the transmission of power and signals can be established between the utility vehicle and the implement. By actuating the power lift cylinders the implement can be raised and its height controlled within certain limits, in order to move between a transport position and a desired operating position. In many cases the implement does not here require its own chassis.
Despite the multiple applications for the three-point implement hitch the spectrum of applications for the motor vehicle is still limited.
The problem underlying the invention is seen as that of developing a motor vehicle of this class in such a way that its spectrum of applications is broadened. In particular the capability of the attachment interface should be expanded in order to open up new areas of application for the motor vehicle.
The motor vehicle according to the invention for industrial and/or agricultural operations contains an attachment interface at the rear of the vehicle or at the front of the vehicle with a three-point implement hitch that is preferably configured according to ISO 730 or DIN 9674. The-three-point implement hitch is carried by a vertically pivoted, telescoping arm connected by a joint to the vehicle chassis, for example, to the vehicle body, a vehicle frame or the vehicle superstructure. A support at the free end of the telescoping arm carries the attachment interface with the three-point implement hitch. Furthermore a locking arrangement is provided by means of which the support can be selectively immobilized with respect to the vehicle chassis when the telescoping arm is, for example, in a retracted and lowered operating position.
As a result of the telescoping attachment interface with a three-point implement hitch, new application areas for the motor vehicle are opened up, in particular for agricultural tractors. It makes possible, on the one hand, the performance of all operations that could be accomplished with a conventional three-point implement hitch. On the other hand, a large loader height is constantly available on the rear end of the vehicle or on the front end of the vehicle. The motor vehicle according to the invention makes possible the movement of implements with enlarged degrees of freedom and a wider range of lifting heights. It can be employed, on the one hand, as conventional tractor with a conventional attachment interface and, on the other hand, as a fully functioning loader.
A preferred application is seen in the case of a normal operating process (plowing) that can be performed and that the implement (the plow) can be raised to such a degree that it can be deposited on a trailer or an elevated deposit location without any additional equipment. Due to the simple, rapid loading, a rapid change between different operating sites, separated by some distance, is possible, in that after one operating application, the implement is loaded onto a trailer, the trailer coupled to the motor vehicle and driven to a new operating location at high vehicle speed. The lifting of implements is possible up to, for example, the height of the upper edge of the vehicle cab, so that the implements can be raised to a height to permit deposit on shelves or trailers without having to remove them first from the three-point implement hitch.
A further advantage of the telescoping attachment interface lies in the fact that the coupling of attached implements and, for example, the carrying with the earth scoop through horizontal movements of the telescopic arm can be accomplished without any movement of the tractor.
Preferably the attachment interface contains, in addition to the three-point implement hitch, further attachment arrangements and/or coupling arrangements that can be fastened to the support. In that way the functions of current day one-point hitches such as towing hooks, towbars, towing coupling and the like can be provided. In all embodiments, towing eyes of an implement to be attached can be taken up from the ground and brought into operating position hydraulically.
Preferably, the telescoping arm is attached in the center with respect to the width of the vehicle, behind the operator""s platform, in particular behind the operator""s cab and ahead of the rear axle, resulting in a telescoping rear interface. Here the motor vehicle may be configured to great advantage as a center seat tractor or a front seat tractor.
According to a preferred embodiment of the attaching implement interface of the present invention, the telescoping arm contains generally an outer pivoting component connected by a joint to the vehicle chassis, and at least an extensible insert that is used to control its length. At the free end of the insert, the support is attached which carries a three-point implement hitch.
According to a particularly simple development of the invention, the telescoping arm contains two concentric components that can be inserted into each other. These may be configured as rectangular profiles that offer a high resistance to torque and that make possible a simple design of the sliding guides and the support points for lifting arrangements. For certain applications, the use of a telescoping arm with at least three components inserted into each other may be advantageous.
According to preferred further developments of the invention, the pivoting and extension movement of the telescoping arm and, if necessary, the relative movement of the support relative to the telescoping arm, is performed by pressurized fluid piston and cylinder units, appropriately by double acting hydraulic cylinders. These can be supplied with pressurized hydraulic fluid by the hydraulic system of the motor vehicle. In particular for the extension and retraction of the components, at least one extension cylinder can be provided between the pivoting component and an extensible insert or in each case between the components of the telescoping arm. Preferably two hydraulic cylinders that act effectively in parallel engage, on the one hand, the vehicle chassis and, on the other hand, the telescoping arm, in order to move the attached implement in the vertical direction.
In order to bring the support into a desired defined direction or to hold it in a defined position, it is advantageous to connect the support by a joint to the free end of the telescoping arm, for example, with the free end of an extensible insert. Between the telescoping arm or the vehicle superstructure on the one hand and the movable support on the other hand, at least one double acting pivoting cylinder is arranged, by means of which the support can be pivoted and directed.
In a number of operations, the implement should maintain a desired orientation relative to the ground, even though the telescoping arm is moved. For this purpose it is particularly advantageous if the pivoting system is configured in such a way that the coupling plane is maintained vertically, or in any other desired orientation, regardless of the inclination of the telescoping arm. For this purpose, a preferred further development of the invention provides a level control arrangement that controls the at least one pivoting cylinder in such a way that the implement is retained in a desired orientation relative to the ground, regardless of the pivoted position of the telescoping arm. To determine a present value signal for the level control arrangement, the direction of the desired orientation of the implement can be monitored by an appropriate sensor with the orientation maintained by the hydraulic control in a known manner.
It has also been shown as advantageous to provide an adapter that can be fastened to the three-point implement hitch which is used to accept special implements whose attachment interface is not defined by the aforementioned standard for a three-point implement hitch. This combination can replace a conventional front loader. This configuration makes it possible, for example, to perform all operations that were previously accomplished with a front loader as long as the front loader implements (earth scoop, stackerfork etc.) are fastened by means of special adapters to the three-point implement hitch.